1. Field of the Invention
The invention relates to a bend-straightening machine for long workpieces, said machine having workpiece holding fixtures on a machine base to grip the ends of the workpiece in a rotatable manner, having at least two straightening bases arranged a distance apart on the machine base for support of the workpiece in its vertical direction, having at least one straightening punch arranged between the straightening bases to act upon the workpiece as well as having an actuating mechanism which can be moved towards the workpiece and away from it by means of a driving mechanism.
2. Description of the Related Art
A bend straightening machine of similar concept is known from U.S. Pat. No. 5,839,315, owned by the assignee of this application. In U.S. Pat. No. 5,839,315, the actuating mechanism is based upon cam on roller technology, which utilizes a camshaft mounted in the machine table below the straightening bases. The actuating mechanism is designed as a bridge which holds the straightening ram in vertical alignment of the workpiece and the bridge can be moved in a vertical plane by means of a drive mechanism coupled to the camshaft. The bridge is spring-mounted on the base plate of the machine to urge the ram to be in constant engagement with the camshaft to ensure precise alignment with the workpiece.
The known bend-straightening machine has a fundamental disadvantage in that the tonnage and stroke capability of the machine are limited by ergonomic considerations when considering the floor-to-workpiece centerline distance. Also, due to the plurality of springs supporting the bridge, deformation of any of springs will lead to an asymmetrical load on the workpieces.
The object of the present invention is to further refine a bend-straightening machine of the type stated above which provides for precise, directionally accurate straightening of the workpiece while at the same time allowing machine tonnage and ram stroke to be considered separately from ergonomic floor-to-workpiece centerline considerations.
The objective of the subject invention is attained in a bend-straightening machine of the type stated above in such a manner that the actuating mechanism is designed as a ram which holds the straightening punch in the vertical alignment of the workpiece and said ram can be moved in the vertical plane by means of the actuating mechanism. The actuating mechanism in this case consists of cam on roller technology which utilizes a camshaft which is mounted to a rigid machine frame above the workpiece centerline. In this case of a rotationally symmetrical workpiece, vertical alignment is understood to be its axis.
Particular significance is attached to placing the cams and camshaft above the workpiece centerline in this bend-straightening machine, in that, cam design can be considered separately from ergonomic workpiece centerline-to-floor distance considerations. Additionally, this machine concept maintains all the advantages of precise, directionally accurate straightening known from U.S. Pat. No. 5,839,315.
The invention described above consists of a rigid machine frame which comprises a machine base, vertical posts, and a machine top plate. Advantageously mounted within the machine frame is the ram which is supported perpendicular to its direction of movement by linear guides mounted to the vertical posts.
A particular embodiment of the invention provides for the ram to be spring-mounted to the machine top plate. The advantage of spring-mounting the ram is that the drive mechanism exclusively serves the purpose of moving the straightening punch which is supported in the ram in the direction of the workpiece, and the latter against the force of one or more springs which act between the machine top plate and the ram. By having a spring centrally located on the machine top plate and ram guided by linear guides, the ram will always provide a symmetrical load on the workpiece.
Advantageously, the drive mechanism has a motor and a shaft propelled by it as fixedly mounted units and at least one cam disk fixedly joined to the shaft, said cam disk interacting with a projection of the ram. The movement of the ram thus takes place by means of a driven cam disk which interacts with the projection on the ram. Basically, such a construction is suitable for producing both the downward motion as well as the upward motion of the ram. If the projection rests against the outside of the cam disk and a spring exerting a restoring force acts upon the ram, the spring ensures that the projection always rests against the cam disk and is more or less raised or lowered depending on the particular angular position of the cam disk. However, it is also conceivable to provide the disk with a groove in the shape of a curve in which the projection engages essentially without play when seen across the breadth of the groove. Depending on the angular position of the cam disk, the projection which produces the connection to the ram is actively raised or lowered. The projection is advantageously designed in the form of a roller so that the relative motion between the projection and cam disk can take place largely without friction.
An embodiment of particularly simple design provides for the shaft to be rotatably supported on bearings mounted to the machine top plate and for cam disks to be connected to the shaft at opposite sides of the machine top plate, said cam disks interacting with projections.
If present, the springs producing the upward movement of the ram should be designed as compression springs placed between a spring mounting bracket and the top surface of the machine top plate.
Additional features of the invention are presented in the dependent claims, the description of the drawings and in the drawings themselves, whereby it is pointed out that all individual features and combinations of individual features are essential to the invention.